Electrolytic cell structure



March 12, 1963 D. w. MORGAN 3,081,254

ELECTROLYTIC CELL STRUCTURE Filed June 24, 1958 4 Sheets-Sheet 1 IEZIE- :L .1

/3/ )4 /5 v (/4 V5 V5 INVENTOR. :E :I: ET- En 94V/d- /4/ A40/"gm March 12, 1963 D. w. MORGAN 3,081,254

ELECTROLYTIC CELL STRUCTURE Filed June 24, 1958 4 Sheets-Sheet March 12, 1963 D. W. MORGAN ELECTROLYTIC CELL STRUCTURE Filed June 24, 1958 4 Sheets-Sheet 5 INVENTOR. Dar/a h/ A40/ya BY/..

March 12, 1963 D. w. MORGAN 3,081,254

ELEcTRoLYTIc CELL STRUCTURE Filed June 24, 1958 4 sheets-sheet 4 INVENTOR. m//a h( Marga/7 BY i@ IAM..

` rupting the cathode' surface or interfering with the United StatS e U 3,081,254 w v.. vELECTROLXTIC. CELL STRUCTURE David W. Morgan, Los Altos,`( -alif. assigner to Kaiser Aluminum & ChemicalCorporation, Oakland, Calif., a corporation of Delaware H Filed June 24, 1958,Ser.,N`o'. 744,162

20 Claims. (Cl. 20A- 244) n Ourl invention' relates in general to electrolytic cells for the production of metal. More particularly, the invention relates to new and improved arrangements for refractory hard metal cathodic current conducting elements for aluminum reduction cells. As used hereinafter,

3,081,254 Patented Mart 1963 ICC electrolyte and/or metal. The forces are morefof a prob# lem in cells employing RHM elements than in conventional cells because ofthe greater distance the current must travel in 4the cathode metal layer. Y

The arrangement of -cathodic elements discussed above have failed to offer solutions to these problems. For example, a cell with horizontal side entering cathodic ele- K ments, (l) above, has exhibited difficulties w-ith muck the expression RHM` means refractory hard meta.

f The use of RHM negative current conducting elements, i.e. cathodic elements, `in aluminum reduction cells has been previously disclosed in French Patent l1,064,743. In thelFrench patent there are revealed three arrangements of RHM cathodic current conducting elements for use `i n aluminum reduction cells. AThese `three arrangements `are (1)' horizontal side entering wherein the elements extend horizontally through the vertical, side walls of the` reduction cell and projectattheir interior extremitiesinto the inolten aluminum layer, (2) top' entering elements whereinthc elements pass throughthe solidifiedV crust and molten electrolyte along the sidewalls of the cell Y and terminate at their extremities a short distance above the base of the cell, and (3) the current conducting elements are disposedl vertically 4and introduced into ,the molten electrolyte layer through the base of the electrolytic cell. In all of these arrangements the cathodiccurrent conducting elements are distributed along the length ofthe cell cavity or chamber. u

All `of the above-described arrangernentsfforv RHM cathodic current-conducting elements have' signiiicant disadvantages. One f the problems encountered in the operation of electrolyticcellsemploying suchv elements is mechanical `breakage of the clcrnentsb AThe elements under ythe Vcathode metal layer and with excessive ledging oftrozen bath enveloping the eathodic elements. In this arrangement, electromagnetic disturbancel has been exces- V sive, `and the total distance traveled by the current is more lthan `is desirable. In cells'with top entering cathodic elements along the side walls of the cell',Y (2) above, the elementsinterfere with normal cell operations, particularly with breakingin ofthe crust at the -sides of the cavity; This arrangement has problems with electro magnetic disturbances and muck, also. In cells wit-hpbottorn enteringv cathodic elements, (3) above, the elements are` very susceptible to damage during raking. Also,

the total distance the current must travel in this arrangement isexcessive. p t l As used here inthe specification and the claims, the expression RHM or refractoryhard metal refers to a material which possesses a low electrical resistivity; a low solubility in molten aluminum and molten electrolyte under cell operating` conditions, i-s Wettable by molten aluminum under cell operating conditions, and has good stability under conditions existing at the cathode of a reduction cell.VV The preferred refractory hard 4metal material for at least that portion' of the surface of such element in contact with the molten aluminum consists essentially of" at least one of the materials selected from the group consisting of the carbides'and borides of timay be broken by `abuse-during raking, by stress imposedI through adheringcrust during anode adjustment,` or Aby A further problem lies in preventing muck (aloose mixture of undissolved alumina yand' frozen velectrolyte` or bath which sinks through the cathode metal layer) from building up under `the cathode. rnetal layer and dis necessary -ow of current -in thecathode metal layer.` VThis problem is morepronounced in cells employinglRHM ,current `conducting `elements than it is in' conventional tanium, zirconium, tantalum, and niobiumpand mixtures thereof, such materials being found to exhibit all or substantially all of the above properties.

`The expression cons-ists essentially, as used herein- Vafter in the` specification and therclairns, means that the -RHMamaterial does Ynot contain other substances in g amounts suicient to materially affect the desirable char` acteristics of the material, although other substances may .be present in minor amounts which do not materially affect such desirable characteristics, for example, small proportions of oxygen, nitrogeny and iron' in titanium boride. m,

Therefore, it is the principal object of the invention to.

p present new and improved arrangements for RHM cathod-` cells employ-ing steel collector bars embedded in a carbon bottom wallY or floor because the net heat flow across the bottom surface of the cavity is away from the'fcavity rather than into the cav-ity as inthe case of conventional cells, thereby. making the muck lying onfthe bottom of theA cavity cooler than the adjacent cathode' metal.4 This t makes the `muck `harderand morev diicultrt remove.

A further problem lin-tlie operation of electrolytc cells employing RHM cathodiccurrentvconducting elements` Ylies in the effect of `turbulence `frornelectromagnetic forces induced in the `metalna'nd the electrolyte" by the magnetic telds resultingfrom the heavy electrical currents required for the reduction process. 'Iheseforces may cause excessive movement and surging of the molten ic current-conducting elements for aluminum reduction cells whichwovercorne or substantially reduce the .disadvantages of'prior art arrangements.

It is a further object of the invention to present Vimprovedarrangements `for RHM current-conducting cathodic elements wherein the` elements will not be .sub-

ject to mechanical breakage during operation of the elec-` y trolytic cell.- p

It is also an object of theinvention to provide improved m arrangements of RHM cathodic elements for aluminum vreduction cells, said arrangements permitting cell opera# tionwith maximum convenience and minimum maintenancelabor, and skill on the part of the operators.

It isua still further object of the invention to provide an improved design for an electrolytic cell employing n RHMcathodic current-conducting elements wherein the total distance through .which the current must travel in and between cells is substantially lessened.

It is also an object of the inventionto provide. ani

arrangement fora plurality ,of 'electrolytic cells employing RHM cathodic',.currentfconducting elements wherein they total distancev through which the current must' travel in and betweeny cellsis substantially lessened. Y

It is a still further object of the invention to provide improved arrangements of RHM cathodic current-conducting elements for aluminum reduction cells wherein the elect of electromagnetic forces in the electrolyte and metal in the cell is minimized thereby preventing excessive movement and surging of the electrolyte and/ or metal.

These and other objects and advantages will be apparent from the ensuing description of the invention when taken in view of the accompanying drawings.

The invention generally comprises arrangements for RHM cathodic current-conducting elements for elongated (that is, the side walls are relatively longer than the end walls) aluminum reduction cells or pots which are electrically connnected in series in a potline. The elements are disposed in the cells in one or more rows transversely across the cell, that is, across the width or shortest horizontal dimension of the cell. One extremity of each cathodic current-conducting element is adapted to extend into the molten aluminum pool of the cell while the other extremity is exposed to the atmosphere and is connected to a metallic conductor. The arrangements are suitablev for electrolytic cells employing either prebake anodes or self-baking (Soderberg) anodes. By disposing the elements in at least one row transverse across the cell, the cell can be operated with maximum convenience, and minimum maintenance, labor, and skill on the part of the operator. Furthermore, placement of the elements according to the invention lessens the total distance through which the current must travel in and between cells in order to perform its function of reducing an aluminum-containing compound, e.g. alumina, to make aluminum metal. Also, the arrangements for the elements as taught herein substantially reduces electromagnetic disturbance of the molten metal and electrolyte which has been 'excessive in previous electrolytic cells employing RHM cathodic current-conducting elements.

In the accompanying drawings are illustrated several embodiments of the instant invention as applied to aluminum reduction cells.

In the drawings:

FIGURE 1 is a plan view of a plurality of elongated aluminum reduction cells connected electrically in series and shows an embodiment of the invention wherein the cells are arranged in side by side relationship;

FIGURE 2 is a view taken along the line 2-2 of FIGURE l;

FIGURE 3 is a view taken along the line 3 3 of FIGURE 1;

FIGURE 4 is a plan view of a plurality of elongated aluminum reduction cells showing a further embodiment of the invention as applied to cells arranged in side by side relationship;

FIGURE 5 is a view taken along the line 5 5 of FIGURE 4;

FIGURE 6 is a view taken along the line 6 6 of FIGURE 4;

FIGURE 7 is a plan view of a plurality of aluminum reduction cells connected electrically in series and showing an embodiment wherein the cells are placed in end to end relationship;

FIGURE 8 is a view taken along the line 8 8 of FIGURE 7;

FIGURE 9 is a view taken along the line 9 9 of FIGURE 7;

along the line 12 12 of The elongated cells 10 are electrically connected in series and are placed in side by side relationship, that is, the side wall of one cell is parallel and adjacent to a side wall of a neighboring cell. Each cell 10 has a metal shell 11, e.g. of steel, within which is disposed in the usual manner an insulating lining 12 which can be of any desired insulating material, such as alumina, bauxite, clay or aluminum silicate bricks. Within insulating lining 12 is disposed refractory lining 13, which can be of any desired material, for instance, carbon, alumina, fused alumina, silicon carbide, silicon nitride bonded silicon carbide or other desired materials. Most commonly the lining is made up of a plurality of carbon blocks or is a rammed carbon mixture or a combination of a rammed carbon mixture for the bottom or floor of the lining with side and end walls constructed of blocks of carbon. Alternatively, the side and end walls can be constructed of silicon carbide bricks or other suitable material. The lining 13 defines a cavity or chamber within which is disposed a pool or layer of molten aluminum 14. Also disposed within the chamber and in contact with the aluminum layer 14 is a body or layer 15 of molten electrolyte, e.g., cryolite. The electrolyte 15 is covered by a solid crust layer 16, which consists essentially of frozen electrolyte constituents and additional alumina. As alumina is consumed in electrolyte l5, the frozen crust is broken and more alumina fed into the electrolyte.

Disposed above cells 10 are anode bus bars 17 which are supported by any suitable means (not shown). Prebake anodes 18, for introducing electrical current into the cell, are shown supported from bus bars 17 by means of rods 19 which are connected to bus bars 17 by any suitable means, such as by clamping. Anodes 18 are preferably rectangular carbon blocks and are disposed within the chamber defined by the walls and Hoor of the cell in rows parallel to the longitudinal axis of the cell. Anodes 18 depend downwardly into the body of molten electrolyte 15. Bus bars 17 are H-shaped, as shown in FIGURE 1, and the current from the adjacent cathode bus 20 flows to the center of anode bus 17 and then ows equally towards the ends of bus 17.

Cathode bus bars 20 are supported by suitable means (not shown) above cells 10. RHM cathodic elements 21 are connected to cathode bus bars 20 by suitable means and are disposed transversely in at least one row across the longitudinal midsection of cells 10. In FIGURES 1, 2 and 3, two rows of elements 21 are shown disposed transversely across the cell. Elements 21 depend vertically downward and extend down into the molten aluminum pool 14. The elements may extend from cathode bus bar 20; however, this requires a relatively long length of RHM material which would substantially increase the cost of the element. A more economical design is as shown in FIGURES 1, 2 and 3 wherein relatively short elements 21 extend from just above the crust layer 16 down into the molten aluminum layer 14. Suitable metallic conductor members, e.g. of aluminum, 23 are joined by suitable means to elements 21 which are in turn joined by suitable means to cathode bus members 20.

The RHM elements may be joined to aluminum conductor members by a procedure which is disclosed in the co-pending application of Jack L. Henry, Serial No. 729,621, led April 2l, 1958. This procedure generally comprises a cleaning of the RHM member at the portion of the surface where the joint is to be made, preheating the RHM member to a temperature above the melting point of aluminum, contacting the RHM member while at said preheating temperature with a molten llux consisting essentially of the uorides of sodium, aluminum and lithium and sodium chloride, and then contacting the RHM member with molten aluminum after which the RHM member and aluminum are allowed to cool. The joint which is formed between the RHM member and the aluminum has superior mechanical strength and electri cal conductivity characteristics.

ilreferabl'y, suitable membersr are disposedwithin the cell to protect elements 21tfrom damage during crust ,breaking operations. An example of suitable means `are "rigid frame members 24"which are transversely disposed across 'the cells 10 adjacent elements21 and fastened to bars of one cell are connected to the cathode bus of an adjacent cell by means of llexible metal connections 22 which are j suitably joined to anode bus bars 17 and vcathode `bus bars 20 byany suitable means, such asV welding. i

By placing the elements transversely across the midsections of cells 10, the problem of growth `of muckdevposits under the cathode metal `is substantially reduced since the entire ends of the cellsare free of RHM `ele-V ments` and open to efficient raking.` In` addition, muck may be 4raked to both sides and ends `of the cell, where itcan come incontact with'the electrolyte and be dissolved. Further help in controlling muck is afforded by the electromagnetic characteristics' of the cells shown inl FIGURESl, 2 and 3, wherein the cathode metal Awill ilow more rapidly in the midsection of the cell and more slowly towards the ends, thereby promoting removal of muck from the midsection of the cell and depositing it towards, the ends. a

The electromagnetic forces in the cell depicted. in FIGURES 1, 2' and 3 are substantiallyreduced and are useful in controlling muck. The reduction of the electromagnetic forces in the cells may be ascribed to the fact that in the critical region in the midsection of the 'cell where the current in the cathode metal is greatesaxthe magnetic fields set up `by the currents in the two lend halves of theanode .bus bars are compensating, since the current travels out from the midsection of the anode [bus in equal amounts but 'opposing directions in` each side.' Inra similar manner the fields set up by the currents coming into the elements `in the midsection of tne cell through the cathode metal layer `tend to compensate.

Further, .the problem of electromagnetic.` surgingof the cathode metal is further reduced by the effect of theele-v ments in damping end-to-endmovement of metal. The elements form a'barrierzacross the" cell, thereby `appre-` ciably restricting the ilow of metaland electrolyteV past the `rnidsection of the cell. Y

Placing the'elements transverselyacross the midsections-of the cells does not interfere with` rakingmuck in the cells, anode setting, orbreaking-in the side crust.

` In the embodiment shown in FIGURES l, 2 'and 3, the

alumina may be fed tothe cells in the conventional manner by breaking crust in the center of the cellrbetween the Vlongitudinal rows of anodes with a poker and then puddling in the alumina. Further, the poker yernployedtoffeed the celland to yrake muck. in the bottom 1 may be made shorter than in cells of other designs, since thepoker does riot need to reach past the midsectionof the cell, but only up yto the elements. `With a shorter FIGURES 4, 5v and 6 depict a 'further lembodiment of the invention for electrolytic cells connected electrically in series yand placed in side-by-side relationship. In these FIGURES, each cell 30 has a metalshell 31, e.g. of steel, within which is disposed in the usual manner an insulating'lining 32 which can be of any desired insulat- =ing material, such` as alumina, bauxite, clay `or aluminum silicate bricks. Within insulating lining 32 is disposed refractory lining 33, which can be of any desired ma# terialjf-or instance, carbon, alumina,'fu'sed alumina, sili` con carbide, silicon' nitride bonded silicon carbide or other desired materials. The lining 33 defines a cavity or chamber .within which is disposed a pool or layer of molten aluminumv 34. Also disposed within the chamber and Acontact with the aluminum pool 34 is a body 35 of molten electrolyte, e.g. cryolite. The electrolyte 35 is covered by solid crust layer 36, Whichco'nsists essentially of frozen electrolyte constituents and additional alumina.

Disposed above cells 3) are anode bu's bars 37 which are supported by any suitable means (not shown). APrebake anodes`38 for introducing electrical current into the cell are shown supported from bus ba`rs`37 by means of rods 39 which are connected to bus bars 37 by any suitable means, such as by clamping. Anodes 18 are `preferably rectangular carbon blocks and disposed within theV chamber denedby the walls and iloor vof the cell in. rows parallel to` the longitudinal axis 'of the cell. Anodes 38 depend downwardly into the body of molten electrolyte 35. Bus bars 37 are H-shaped, and, as shown in FIGURE 4, two such bus bars are disposed above each cell. The current from an adjacent cathode bus flows to an anode bus 37 at the midway point and then flows equally towards 'the ends of bus 37.

Although the embodiment in FIGURES A4, 5 andy`6 depicts two H-shaped anode bus bars. disposed above each th:: cell of the two H-shaped bus bars depicted inv FIGJ' poker it is easier to rake muck from under the end'anodes,

where with anormal poker, raking is a problem'. Also,

vthe need for anode adjustment is greatly reduced by the reduced problems of muck andthe increased stability of thecathojde metal which results from the more favorable electromagnetic and current-flow characteristics. v

The total distance through which the current must flow in'. the cells depicted iriFlGURES 1 through 3 is less than in those arrangements where the current mu'st,passV either beyond the ends of the cell, asin all end-fed-bus arrangements, or Ibeyond the sides of the cell as in all arrangements employing cathode ring bus.

cell, the embodiment is not limited thereto. A satisfactory arrangement of one bus bar disposed above the cell is one comprised of two parallel members disposed parallelto the long dimension of the cell and joined by two cross members, one crossV member beingl located above each midway point between the midsection and the end This structure can be simplydescribed' URES 4, 5 and A6. l

,Cathode bus bars 40 are supported by suitable means (not shown) above cells 30.RHM cathodic elements 41 are connected .to bus bars 40 byV suitable means and are disposed transversely across the cells 30 in two rows, one row being .at each midpoint between the midsection and the ends of the cells. Elements41 depend vertically downward `and extend into the molten aluminum pool 34., In FIGURES 5 `and 6 the elements 41 are shown as relatively short elements extending fromfjust above the crust layer 36 down into the molten aluminum lpoo'l Suitable metallic conductor members, eg. of aluininum, 43 are joined by suitable means Vto elements 41 Vand are m turnV joined by suitable means to cathode bus members 40. Rigid frame members 44 are transversely disposed across the cells 30 adjacent to andon either side `of, the transverse rows of elements 41, said members 44 depending downwardly into crust 36.

In the cells depicted in FIGURES 4, S and 6, the elec-v tromagnetic forcesl are reduced to a levelwithin vthe order of that foundin present day cells and are even useful in controlling the problem of muck. The magnetic fields set up by the currentsin the two end halves of each H-shaped `anode bus are compensating, and in a similar manner the fields set up bythe currents coming into elements 111` which are'disposed in two transverse rows, onel row being at substantially each of the halfway or midway'points be"- tween the midsection and ends of the cells,` tend to coml pensate. Also, the' problem of electromagnetic surging of the cathode metal is reduced by the effect of the elemet's 7 damping end to end movement of metal. The elements 41 form barriers across the cell which will appreciably restrict the flow of metal and electrolyte.

FIGURES 7, 8 and 9 show an arrangement for RHM cathodic elements for electrolytic reduction cells electrically connected in series and arranged in end to end relationship. The elongated cells 50 are electrically connected in series and are placed in end to end relationship, that is, an end wall of one cell is parallel and adjacent to an end wall of a neighboring cell. Each cell 50 has a metal shell 51, e.g. of steel, within which is disposed in the usual manner an insulating lining 52 which can be of any desired insulating material, such as enumerated previously in description of FIGURES 1, 2 and 3. Within insulating lining 52 is disposed refractory lining 53, which can be of any desired material as described previously. The lining 53 denes a cavity or chamber within which is disposed a pool or layer of molted aluminum 54. Also disposed within the chamber and in contact with the aluminum 54 is a body 55 of molten electrolyte, e.g. cryolite. The electrolyte body 55 is covered by a solid crust layer 56.

Disposed above cells 50 are anode bus bars 57 which are supported by any suitable means (not shown). Selfbaking anodes 53 for introducing electrical current into the cell are electrically connected to bus bars 57 and are supported by .suitable means (not shown). It is usual practice with self-baking anode cells to employ a single anode per cell; however, more anodes, e.g. two anodes, could be used. The anodes 58 depend downwardly into electrolyte 55.

Cathode bus bars 60 are supported by suitable means (not shown) above cells 50. Relatively short RHM cathodic elements 61 are joined by suitable means to metallic conductor elements 63 which in turn are joined by suitable means to cathode bus bars 60. The elements are disposed vertically and transversely in at least one row across the downstream end of each cell, that is. the. end nf the cell where the current leaves the cell and enters the anode bus of an adjacent cell. Elements 61 depend downwardly from above the crust 56 and extend through electrolyte 55 and into the molten aluminum pool 54.

Rigid frame members 64 are disposed transversely 'across theV cells 50 adjacent to elements 6l, said members 64 depending downwardly into crust 56.

As shown in FIGURES 7, 8 and 9, the cells 50 are lelectrically connected in series, that is, the cathode bus bars of one cell are connected to the anode bus of an adjacent cell by means of flexible metal connections 62 which are joined to cathode bus bars 60 and anode bus bars 57 by any suitable means, such as welding.

FIGURES 10, 1l and l2 show an alternative arrangement for RHM vcathodic elements for electrolytic cells arranged in end to end relationship. The elongated cells 70 are electrically connected in series and are placed in end to end relationship. Each cell 70 has a metal shell 71, eg. of steel, within which is disposed an insulating lining 72 which can be of any desired insulating material as discussed previously. Within insulating lining 72 is disposed refractory lining 73 which can be of any desired material as previously discussed. The lining 73 defines a cavity or chamber within which is disposed a pool or layer of molten-aluminum 74. Also disposed within the chamber and in contact with the aluminum pool 74 is a body 75 of molten electrolyte, e.g. cryolite. The electrolyte 75 is covered by a solid crust layer 76 which consists essentially of frozen electrolyte constituents and additional alumina. Disposed above cells 70 are anode bus bars 7.7 which are supported by any suitable means (not shown). Self-baking anodes 78 for introducing electrical current into the cell are electrically connected to bus bars 77 and are supported by suitable means (not shown). Anodes 78 depend downwardly into electrolyte 75.

= Cathode bus bars 80 are supported by suitable means (not shown) and are disposed across the downstream end of said cells 70. Cathodic elements 81 are connected to cathode bus bars by suitable means and are disposed transversely in at least one row across the downstream end of said cells 70. Elements 81 extend horizontally through suitable openings provided in the metal shell 71, insulation layer 72 and refractory lining 73 with the inner extremity thereof projecting into the layer or pool of molten aluminum 74. The cells 70 are electrically connected in series, that is, the anode bus bars are connected to the cathode bus of an adjacent cell by means of exible metal connections 82 which are suitably joined to anode bus bars 77 and cathode bus bars 80 by any suitable means such as welding.

Cells 70 are electrically connected in series, that is, the cathode bus bars of one cell are connected to the anode bus of an adjacent cell by means of exible metal connections 82 which are joined to cathode bus bars 80 and anode bus bars 77 by any suitable means, such as welding.

In the embodiments shown in FIGURES 7 through 9 and FIGURES l0 through 12, the placing of the cathodic elements transversely across the downstream ends of the cells substantially reduces the problem of mechanical breakage of elements during raking and feeding, since the elements are grouped at the end of the cavity away from the regions of feeding and raking. Also, in the embodiment shown in FIGURES 7 through 9, mechanical breakage of the vertical refractory hard metal elements by crust movement is precluded by the rigid frame members.

The problem of maintaining direct contact between the RHM elements and the cathode metal is alleviated by both embodiments since the elements are grouped together in the downstream end of each cell where a maldistribution of current due to a dead section of anode will have little effect and cannot cause ledging which would cover the elements. The problem of growth of muck deposits under the cathode metal is also alleviated because the chamber or cavity is substantially free of cathodic elements and open to eliicient raking. Muck accumulation at the downstream end where the cathodic elements might impede raking will be repressed by movement of the metal caused by electromagnetic forces.

The electromagnetic forces in the arrangements shown in FIGURES 7 through 9 and FIGURES 10 through l2 will be kept to an acceptable level by the disposition of the RHM elements across the width of the chamber or cavity and by the high and widely-spaced arms of the anode bus, which are usual in self-baking (Soderberg) cells. The region of greatest electromagnetic forces in the cell will be at the downstream end, where electromagnetic force is desirable to gain sulicient metal movement to inhibit muck accumulation near the elements. Moreover,v the arrangements shown in FIGURES 7 through 9 and FIGURES l0 through 12 improve cell operation since in each embodiment the elements are grouped away from the region of the chamber requiring raking, and from the region in which the cell is fed alumina. The region near the refractory hard metal elements themselves will require little attention since this area or this region is kept clean by the movement of the cathode metal. Also, the current must ow is minimized.

Although, in the embodiments depicted in FIGURES 1 through 3 and FIGURES 4 through 6, prebake anodes are specifically shown and discussed, it is to be understood that these embodiments may also be employed with reduction cells employing self-'baking (Soderberg) anodes. Likewise, in the embodiments depicted in FIGURES 7 through 9 and FIGURES 10 through 12, wherein self-baking (Soderberg) anodes are specically shown and discussed, it is to be understood that these embodiments may also be employed with prebake anodes. Further, it is to be distinctly understood that the invention is not limited to the illustrative embodiments presented and that various changes may be made without departing from the spirit and scope thereof, the invention being limited only as the total distance through which.

defined in the following claims wherein what is'clainied is: fll A plurality of elongated electrolytic cells'for the production of aluminum, said cells connected Velectrically in series `and having an arrangement of'cathodic currentconducting elements, each cell' comprising refractory side and end walls, saidside walls being relatively longer than i Y to contain a moltenV aluminum pool in thelower portion said end walls, a floor of a refractory material, said walls and said floor defining achamber adapted tocontain a molten aluminum pool in the lower portion thereof and a'body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially within said chamber and adapted vto be in contact with the` molten electrolyte, said arrange.-

ment of cathodic current-conducting elements consisting ofA at least one row across the shortesthorizontal dimension of said cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool.

andthe other extremity exposed to the atmosphere and connected to a metallic conductor, at least that portion of the surface of said current-conducting element in con-` tact with said molten aluminum consisting essentially of refractory metallic compound; v

v 2. Applurality of elongatedelectrolytic cells for the production of aluminum, saidcells connected electrically in series andhaving an arrangement of cathodic currentconductingelements, each cellcomprising refractory side andend walls, said side walls being relatively `longer than said end walls, a floor'of a refractory material, said walls Y and said floor definingk a chamber adapted to contain a molten aluminum poolin thelower.- portion thereof and a body of molten electrolyte abovesaid molten aluminum pool andin contact therewithat least one anode member disposeduat least partially within said 'chamber and adapted to be in contact with the molten electrolyte, said arrangement of cathodic current-conducting,elements consisting of at least one ro"w parallel to said end walls, oneI extremity ofeach cnrrent-conductingelement being adapted ,to `ex-V t tend into said molten aluminum pool and the other ex-` thereof and a body ofmolten electrolyte above said molten aluminum pool and in contact therewith, prebake anode-s disposed at least partially within said chamber in rows parallel to the longitudinal axis of the cell and adapted to be in contact with the molten electrolyte, said cells being arranged in side by side Vrelationship with a side wall of one cell parallel and adjacent to a side wall of a neighboring cell, said arrangement of cathodic, current-conducting elements consisting of cathodic current-conducting elements disposed vertically and transversely in at least one row across the longitudinal midsection of each cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essen# tially of-at least one of the materials selected from the groupvconsisting of the carbides and borides of titanium,: zirconium, tantalum and niobium.

- production of aluminum, Asaid cells connected electrically in series and having an arrangement of 'cathodic currentconducting elements, each cell comprising refractory side andend walls, saidside walls being relatively longer than said end walls, a oor of a refractory material, said walls and said iioor defining -a chamber adapte'dlto containfa molten aluminum p'ool in the lower portion `thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially within said chamber and adapted to be in contact with the moltenelectrolyte, said cells being arranged in end-to-end relationship with an end wall of one cell parallel `and adjacent to an end wall of a neighboring cell, saidarrangement of cathodic current# conducting elements consisting of cathodic, current-conducting elements disposed transversely in at least one row tremity exposed toy the. atmosphere and connected Ato a i metallic conductor, at least that portion of the surface of said current-conducting element in contact with said molten` aluminum consisting essentially of refractory metallic compound. i V j 3`. plurality of elongated` electrolytic cells for the production of aluminum, said cells connected `electrically in series and having `an arrangement of cathodic4 currentconducting elements, -each cell comprising refractory side anderid walls, saidl side walls being relatively longer than said end walls, a oor of a refractory material, said walls and said floor defining a chamber adapted tocontain a molten aluminum pool inthe lower portion thereof and a'body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially withinsaid chamber and adapted t'o'b'e iricont'act with the molten electrolyte, said arrangef ment of cells being arranged inside by side relationship with a side wall of one cell paralleland adjacent to a sidel wall of a neighboring' cell, said arrangement of cathodic,

current-conducting elements consisting of `catliodic currfe`ntcoriducting elements disposed verticallyandV transsection of each cell, one extremity of each currentfconducting element adapted to extend into said molten aluminum pool, atfleast that portion ofthe surface of said currenti T vers'ely in at least one row across the longitudinal mid-` currentfconducting elements, each cell comprisfng re'fractry side and end walls, said side walls being "relatively longer than said end walls, a iioor of a refractory mate; rial, said walls and said oor defining a chamber adapted across the downstream end of each cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in ycontact with said molten aluminum consisting essentially of at least one of the materials selectedV from the group consisting of` the carbides andborides of titanium, zirconium, tantalum and niobium. k n l 6,. A plurality of elongated, self-baking anode electro# lytic -cells for the production of aluminum,l said cell-s connected electrically in series and having' an arrangement of cathodic current-conducting elements, each cell comprising refractory side and end walls, said side walls being relatively longer than said end walls, a iloor of a refractory material, said walls and said oor defining a cham-1 ber adapted to contain a molten aluminum Vpool inthe lower portion thereof and a body of vmolten electrolyte above said molten aluminum pool and in contact there= with, a self-baking anode `disposed at least partially within said cell and adapted to `be in `contact with the molten electrolyte, said cells being arranged in end-to-endrelationship with an end wall of one cell parallel and adjacent to an end wall of a` neighboring cell, saidarrangement of i' cathodic current-conducting. elements consisting of ca-A` thodic, current-conducting elements disposed transversely in at least one row across thedownstream end of each t cell,`vone extremity of each current-conducting element adapted to extend into lsaid molten aluminum pool, at least that portion of the,` surface of sai-d current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

i 7. A plurality of elongated electrolytic cells for the production of aluminum, saidv cells connected electrically in series and having an arrangement vof cathodic currentconducting elements, each cell comprising refractory side and end Walls, said side walls being relatively longer than said end walls, a iioor of a refractory material, said walls,

and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially within said cham-ber and adapted to be in contact with the molten electrolyte, said cells being arranged in end-to-end relationship with an end wall of one cell parallel and adjacent to an end wall of a neighboring cell, said arrangement of cathodic current-conducting elements consisting of cathodic, currentconducting elements disposed vertically and transversely in at least one row across the downstream end of each cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

8. A plurality of elongated, self-baking anode electrolytic celfs for the production of aluminum, said cells connected electrically in series and having an arrangement of cathodic current-conducting elements, each cell comprising refractory side and end walls, said side walls being relatively longer than said end walls, a oor of a refractory material, said walls and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, a self-baking anode disposed at least partially within said cell and adapted to be in contact with the molten electrolyte, said cells being arranged in end-to-end relationship with an end wall of one cell parallel and adjacent to an end wall of a neighboring cell, said arrangement of cathodic current-conducting elements consisting of cathodic, current-conducting elements disposed vertically and transversely in at least one row across the downstream end of each cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

9. A plurality of elongated electrolytic cells for the production of aluminum, said cells connected electrically in series and having an arrangement of cathodic currentconducting elements, each cell comprising refractory side and end Walls, said side walls being relatively longer than said end walls, a floor of a refractory material, said walls and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially within said chamber and adapted to be in contact with the molten aluminum, said cells being arranged in end-to-erid relationship with an end wall of one cell parallel and adjacent to an end wall of a neighboring cell, said arrangement of cathodic, current-conducting elements consisting of at least one row of cathodic current-conducting elements disposed horizontally through and transversely across the downstream end wall of each cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said currentconducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

10. A plurality of elongated, self-baking anode electrolytic cells for the production of aluminum, said cells connected electrically in series and having an arrangement of cathodic current-conducting elements, each cell comprising refractory side and end walls, said side walls being relatively longer than said end walls, a iloor of aV refractory material, said walls and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, self-baking carbon anodes disposed at least partially within said cells and adapted to be in contact with the molten electrolyte, said cells being arranged in end-to-end relationship with an end wall of one cell parallel and adjacent to an end wall of a neighboring cell, said arrangement of cathodic, current-conducting elements consisting of at least one row of cathodic current-conduct-ing elements disposed horizontally through and transversely across the downstream end wall of each cell, one eXtrem-ity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

ll. A plurality of elongated electrolytic cells for the production of aluminum, said cells connected electrically in series and having an arrangement of cathodic currentconducting elements, each cell comprising refractory side and end walls, said side walls being relatively longer than said end walls, a botto-m oor of a refractory material, said walls and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode member disposed at least partially within said chamber and adapted to be in contact with the molten electrolyte, said arrangement of cathodic, currentconducting elements consisting of cathodic current-conducting elements disposed vertically and transversely in two rows l across each cell, one row being substantially at each midpoint between the midsection and the end walls of the cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at'

least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

l2. A plurality of elongated, prebake electrolytic cells for the production of aluminum, said cells connected electrically in series and having an arrangement of cathodic current-conducting elements, each cell comprising refractory side and end w-alls, said side walls being relatively longer than said end walls, a bottom lloor of a refractory material, said walls and said oor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, prebake anodes disposed at least partially Within said chamber in rows parallel to the longitudinal axis of the cell and adapted to be in contact with the molten electrolyte, said arrangement of cathodic, current-conducting elements consisting of cathodic current-conducting Velements disposed vertically and transversely in two rows across each cell, one row being substantially at each midpoint between the midsection arid the end walls of the cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium.

13. An elongated electrolytic cell for the production of aluminum comprising refractory side and end walls and having an arrangement of cathodic, current-conducting elements, said side walls being relatively longer than said end walls, a floor of a refractory material, said walls and said iioor defining a chamber 4adapted to contain a Vmolten aluminum p'ool in" the lower portion thereof and body,of.molten1electrolyte 'above said molten aluminunrpool and incontact therewith, `at leastone' anode member dispos'eclaft least'partially within said chamber and adapted tobe in contact with the molten electrodisposed in atleast one row across the shortest horizontal dinens'iono'f'sad cell, one extrernity of eachourmolten aluminum pool and the other extremity exposed to the atmosphere and connected to a metallic conductor, at least that portion of the surface of sta-id current-conductingeloiiient` in contact with said molten aluminum consisting essentially of refractory metallic compound;

14'. An elongated electrolytic cell for the production of aluminum comprising refractory side and end walls and having an arrangement of cathodic, current-conduct- 'ing elements, said sidewalls being relatively longer than v said end walls, a oor of a refractory material, said walls and said floor defining a chamberA adapted to contain a molten aluminum pool in the lower `portion thereof and a -body of molten electrolyte'contained in said chamber above'saidmoltenaluminum layer and invcontact therewith, at leastone ,anode member disposed at least part tially withinfsaid chamber and vadapted to` be in contact with the molten electrolyte, said arrangement of cathodic, current-conducting elements consisting of cathodic lcurrent-conducting elements disposed in at least one row parallel to said end walls, one extremity of each currentconducting element being adapted to extend into said molten aluminum pool and the other extremity exposed to theatmosphere and connected to a metallic conductor, s* at leastthat portion of the surface of, said current-conducting element in contactwith said moltenaluminurn consisting essentially of refractory metallic compound.

l5. An elongated prebake anode electrolytic cell for the production of aluminum comprising refractory side and end walls and having'an arrangement of cathodic, currentconducting elements,said side walls being relatively longerthan said end walls, a door of a refractory ,materiaL said walls and `said floor defining a chamber adapted to containk a molten aluminum pool in the lower portion thereof and a body of moltenV electrolyte above said molten aluminum pool and in contact therewith,

current-conducting element in contact with said molten aluminum consisting essentially of at least one of the ma yterials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium. t

16. An elongated electrolytic cell forl the production vof aluminum comprising refractory side and end walls and having an arrangement of cathodic, current-conducting elements, said side walls being relatively longer than said end walls, a floor of a refractory material, said walls and'said floor defining a chamber vadapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum pool and in contact therewith, at least Ione anode` disposed at least partially within said chamber', said arrangement of cathodic, current-conducting elements consisting of cathodic Vcurrent-conducting elementsV disposed vertically and transversely across the downstream end of said cell and being in the form of at least one row, one extremity of each current-conducting element adapted to extend lyte, said arrangement of cathodic, current-conducting ele- .ments consisting of cathodic current-conducting elements 14 i t into' said molten aluminum pool, at leastlthat portion of the vsurface of'said current-conducting element in contact with said molten aluminum consistingessentially of fat least one of the materials selectedfrorn the group" consist:

ing of the carbides and borides of titanium, zirconiurr'i, l

tantalum arid niobium.` .t A f 17. An elongated, self-bakingv anode electrolytic cell for `the production "of faluminum comprising refractory `side and' end walls and having an arrangementof cur-- rentconducting elements's'aid sidewalls being lrelatively longer than said end walls, a floor of a refractory mar terial, said walls and'said floor defining a 'chamber adapted Vto contain a molten aluminum pool in the lower portion thereof and a body of molten Velectrolyte above said molten aluminum pool and in contact therewith, a self baking anode disposed at least partially within-said charn-` ber and adapted to be in Contact with the molten electrolyte, said arrangement of current-conducting elements consisting of current-conducting elements disposed vertically and transversely across the downstream end of said cell and being in the form of 'at least one row, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in i contact with said molten aluminum consisting essentially of'at least one of the materialsselected from the group consisting of the` carbides and borides offtitanium, zirconium, tantalum and niobium.

18.` An elongated electrolytic cell for the production of aluminum comprising refractoryside and end walls l and having an arrangement of cathodic, current-conducting ele-ments, said side walls bein-g relatively longer than said end walls, a oor of a refractory material, said walls and said fioor defining a chamber adaptedto contain a molten aluminum pool in the lower portion thereof and al body of molten electrolyte above said molten aluminum pool and in contact therewith, at least one anode disposed at least partially within said chamber and adapted to be in contact with the molten electrolyte, said arrangement of cathodic, current-conducting elements consisting of at least onevrow of cathodic current-conducting elements disposed horizontally through and transversely across the downstream end wallv of said cell, one extremity of each current-conducting element adapted to extend into said lmolten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from lthe group consisting of the carbides and lborides of titanium, zirconium, tantalum and niobium.

19. An elongated, self-baking anode electrolytic cell for the productionof aluminum comprising refractory side and end walls and having an arrangement of currentconducting elements, said side Walls bein-g relatively longer than said end walls, a floor of a refractory material, said walls and said floor defining a chamber adapted to contain a molten aluminum pool in the lower portionl thereof and a molten electrolyte above said molten alumi-v num layer and in contact therewith, a self-baking anode disposed at least partially within said cell and adapted to be in contact with the molten electrolyte, said arrangement of current-conducting elements consisting of at least one row of currentconducting elements disposed horizontally through and transverselyv across the downstream minurn pool, at least that `portion of the surface ofv saidy end wall of said cell, one extremity of each current-conducting element adapted to extend into said molten alucurrent-conducting element in contact with said molten aluminum consisting essentiallyr of at least one of theV v` materials selected from the group consisting of the carbides and borides of titanium, zirconium, tantalum and niobium. v i

20. An elongated, prebake anode electrolytic cell for the production of aluminum comprising refractory side and end walls and having an arrangement of cathodic,

15 current-conducting elements, said side walls being rela# tively longer than said end walls, a bottom iloor of a refractory material, said walls and said oor defining a chamber adapted to contain a molten aluminum pool in the lower portion thereof and a body of molten electrolyte above said molten aluminum layer and in contact therewith, prebake anodes disposed at least partially within said chamber in rows parallel to the longitudinal axis of the cell, said arrangement of cathodic, current-conducting elements consisting of cathodic current-conducting elements disposed vertically and transversely in two rows across the cell, one row being substantially at each midpoint between the midsecton and the end walls of the cell, one extremity of each current-conducting element adapted to extend into said molten aluminum pool, at least that portion of the surface of said current-conducting element in contact with said molten aluminum consisting essentially of at least one of the materials selected from the group consisting of the carbides and -borides of titanium, zirconium, tantalum and niobium.

References Cited in the tile of this patent UNITED STATES PATENTS 2,866,743 schmitt Dec. 3o, 195s 2,915,442 Lewis Dec. 1, 1959 FOREIGN PATENTS 168,149 Australia June l0, 1954 583,831 Great Britain Dec. 31, 1946 1,064,743 France May 17, 1954 1,119,821 France -..June 26, 1956 

13. AN ELONGATED ELECTROLYTIC CELL FOR THE PRODUCTION OF ALUMINUM COMPRISING REFRACTORY SIDE AND END WALLS AND HAVING AN ARRANGEMENT OF CATHODIC, CURRENT-CONDUCTING ELEMENTS, SAID WALLS BEING RELATIVELY LONGER THAN SAID END WALLS, A FLOOR OF A REFRACTORY MATERIAL, SAID WALLS AND SAID FLOOR DEFINING A CHAMBER ADAPTED TO CONTAIN A MOLTEN ALUMINUM POOL IN THE LOWER PORTION THEREFORE AND A BODY OF MOLTEN ELECTROLYTE ABOVE SAID MOLTEN ALUMINUM POOL AND IN CONTACT THEREWITH, AT LEAST ONE ANODE MEMBER DISPOSED AT LEAST PARTIALLY WITHIN SAID CHAMBER AND ADAPTED TO BE IN CONTACT WITH THE MOLTEN ELECTROLYTE, SAID ARRANGEMENT OF CATHODIC, CURRENT-CONDUCTING ELEMENTS CONSISTING OF CATHODIC CURRENT-CONDUCTING ELEMENTS DISPOSED IN AT LEAST ONE ROW ACROSS THE SHORTEST HORIZONTAL DIMENSION OF SAID CELL, ONE EXTREMITY OF EACH CURRENT-CONDUCTING ELEMENT ADAPTED TO EXTEND INTO SAID MOLTEN ALUMINUM POOL AND THE OTHER EXTREMITY EXPOSED TO THE ATMOSPHERE AND CONNECTED TO A METALLIC CONDUCTOR, AT LEAST THAT PORTION OF THE SURFACE OF SAID CURRENT-CONDUCTING ELEMENT IN CONTACT WITH SAID MOLTEN ALUMINUM CONSISTING ESSENTIALLY OF REFRACTORY METALLIC COMPOUND. 